1. Field of Invention
Aspects of this invention are related to teleoperated minimally-invasive surgical systems, and more particularly are related to controlling orientation of master and slave surgical instrument tips in a teleoperated minimally-invasive surgical system.
2. Art
The da Vinci® surgical system, manufactured by Intuitive Surgical, Inc., Sunnyvale, Calif., is a minimally-invasive, teleoperated robotic system that offers patients many benefits, such as reduced trauma to the body, faster recovery and shorter hospital stay. One component of the da Vinci® Surgical System is a master tool manipulator that a surgeon uses to manipulate a surgical instrument, referred to as a slave surgical instrument.
The master grip of the master tool manipulator is specially designed to be both ergonomic and intuitive for controlling the slave surgical instrument. The surgeon holds the master grip in a particular way using his/her forefinger and thumb, so that targeting and grasping involves intuitive pointing and pinching motions.
To enable intuitive control of the slave surgical instrument, the master grip must be aligned in orientation with the slave surgical instrument tip in the view reference frame of the stereoscopic viewer. The motions of the slave surgical instrument tip follow master motions via teleoperation and are consistent in both directions of motion as well as absolute orientation. If orientation alignment is not achieved, the slave surgical instrument tip may still rotate in the desired direction, but the slave surgical instrument tip neither points in the same absolute direction nor rolls along the same axis as the surgeon is pointing.
The master tool manipulator uses motors in a gimbal assembly to actively align the orientation axes of the master grip with the associated slave surgical instrument tip in view coordinates. This alignment happens automatically before the surgeon engages teleoperation. Moreover, the system automatically preserves this alignment during manipulation of the camera or instrument outer axes.
Specifically, when entering following on the da Vinci® surgical system, the master grip must be aligned with the orientation of the slave surgical instrument tip before the da Vinci® surgical system operates properly in following. The present system performs a master alignment whenever the system transitions from a mode where this orientation alignment may have been compromised (after a tool change, camera clutch, slave clutch, swapping of arms in a 4th arm system etc.).
A master alignment calculates a set of master wrist joint angles that cause the orientation of the master grip to match the orientation of the slave surgical instrument tip, without changing the master grip position. The master wrist joints are then commanded to match the calculated angles using the motors.
The da Vinci® surgical system checks that the master and slave orientations match before allowing the user to enter following. If the orientations don't match (presumably because the user has over powered the master and not allowed the master to complete the alignment) a warning message is displayed and the master alignment is attempted again. This often slows down the surgeon's entry into following and requires a powered master tool manipulator with motors in the gimbal assembly to move master wrist joints into the proper orientation.